garbage collection whoos.....

Hi, We seem to have an over active garbage collector when our system is getting busy. We are running websperhe 3.52 with most of the efixes on AIX. Max and initial heap size are 1 gig. At some point in time the system becomes unresponsive and gc takes up to 80% of cpu time. If we take stats for longer periods of time gc cpu utilization falls below 18% cpu time... Any body seen something like this before?? Or has some insights???